Insulin dependent (juvenile onset) diabetes affects approximately one million Americans. It is especially difficult to control during pregnancy, with resulting fluctuations in glucose blood levels, acetonuria, vascular disease, and amniotic infections, which pose threats to the fetus. Congenital malformations are a known consequence of diabetic gestation, but their relationship to the degree of disease control is as yet unknown. Even less is known about the milder, long-term consequences as well as problems experienced by diabetic mothers in the care of infant and toddler. The proposed study will follow infants born to diabetic and nondiabetic mothers participating in the Diabetes in Early Pregnancy Study (DIEP) (N in each group 160). These insulin-dependent diabetic and control mothers are being very carefully followed throughout the pregnancy, but the DIEP stops with the evaluation of newborns for congenital malformations. The proposed study will extend the follow-up to age three years, all examiners remaining blind to the group to which the mother belongs. Clinic visits will occur in Seattle at 6 and 12 months, and in Seattle and Boston at 18 and 36 months of age; mothers will be contacted by telephone in the interim. Evaluations will focus on possible neurological and growth abnormalities, and deficits in neurobehavioral, cognitive, verbal, attentional, and personal-social competence. Congenital malformations will also be re-evaluated. Two of the five centers involved in the DIEP, Harvard and University of Washington schools of medicine, are involved in the proposed follow-up. Coordination and data analysis will be provided by the University of Washington. Major disciplines involved: Pediatrics, psychology, nursing, biostatistics, endocrinology, neurology. Additional subjects include infants of diabetic mothers who enter the study after the 21st day of gestation (N=c.35). Some data will be collected in Seattle only (0-12 months follow-up; attentional measures at 18, 36 months) or Boston (Kangaroo Box competence measure at 18, 36 months).